Piston for internal combustion motors



Feb. 9, 1937. E. c. LONG 2,070,085

PISTON FOR INTERNAL COMBUSTION MOTORS I Filed May 1, 1953 Patented Feb. 9, 1937 UNITED STATES PATENT OFFICE PISTON FOR. INTERNAL COMBUSTION MOTORS Elmer 0. Long, Grosse Pointe Park, Mich.

Application May 1, 1933, Serial No.'668.88'l

9 Claims. (Cl. 309-41) This invention relates to pistons for internal combustion motors and particularly to pistons formed of lightweight metals or alloys.

The invention has for its primary object to provide a piston made of a material such as aluminum alloy or other like metals which are adapted to operate with a relatively small initial clearness and to provide specific means-on the piston for holding in the piston skirt thrust sides from over expansion, when the piston becomes high- 1y heated.

Another object of the invention is to provide the piston skirt with a solid thrust side and a resiliently flexible thrust side which are cooperably tied to each other in an improved manner.

A further object of the invention is to provide a piston on the pin boss sides of the skirt with an improved formation, to permit outward movement of the pin bosses without distorting the lower part of the skirt, or the compression side of the skirt.

Still another object of the invention is to provide the piston skirt with a flexible thrust side and adjustable means which are cooperable with the flexible side for permitting adjustment of the piston skirt to its original size, after wear on the piston.

A still further object of the invention is to provide the piston skirt with a flexible part on one of the thrust sides which is resiliently yieldable to cylinder wall pressure and the flexible part having resilient means co-actable against the cylinder wall pressure.

Other and further objects will appear in the specification and be specifically pointed out in the appended claims, reference being had to the accompanying drawing, exemplifying the invention,

and in which:-

Figure 1 is a pin boss side elevation of the improved piston.

Figure 2 is a longitudinal vertical sectional view taken approximately on the line lIII of Fig. 1. Figure 3 is a longitudinal vertical sectional view taken approximately on the line IIIIII of Fig. 2. Figure 41s a horizontal sectional view taken approximately on the line IV--IV of Fig. 2.

Figure 5 is a horizontal sectional view taken approximately on the line V-V of Fig. 3.

Figure 6 is an inverted horizontal sectional view taken approximately on the line VI-VI of Fig. 3. Referring by numerals to the accompanying drawing, the piston shown comprises a head I having the piston ring recesses 2 formed in the outside of the side wall 3 of the head and formed integral with and depended from the side wall 3 is the skirt 4- having a power thrust side 5 and a compression thrust side 0.

The piston is of the conventional trunk type having the pin boss sides I integral with the head and skirt and carrying inwardly disposed pin bosses 8, the pin boss sides I however, being relieved or inset as designated at 8 on the periphery of the skirt 4, and formed in each pin boss side 1 in opposite disposition, is an approximate L-shaped slot ID, the vertical extension H of each slot l0 extending upwardly to adjacent the lower piston ring groove 2 and downwardly to the horizontal extension l2 of said slot which is formed on the bottom of respective insets 9 and extending to one end of each inset.

The L-shaped slots It are cut or extend through the thickness of the pin boss side I of the skirt 4, the vertical. extension ll of each slot being cut into respective pin bosses 8 as shown in Figs. 1, 3, and 4, and each pin boss on one side being cut away from. the skirt as designated at l3 in Fig. 4, adjacent each vertical extension I I of the slots l0. Paralleling each vertical extension ll of respective slots I0, is a vertical slot. l4, said slots I4 extending from the bottom of the inset 9 in alinement with a respective transverse extension l2 of the slot iii, to and into the lower piston ring groove 2 wheresaid slots I! join a transverse slot I5 formed in and cut through the thickness of the piston head wall 3.

Each slot I4 is formed on one end of respective insets 9 on the pin boss sides 1, the slot I 4- and the slot I0 on each pin boss side I, forming a supporting leg l6 which extends from the side wall 3 of the head, said legs being for the support of the cylinder bearing portion ll beneath each transverse extension I! of respective L- shaped slots 10 as well as being for the support of the upwardly extending tongue shaped portion l8 which is formed on the compression thrust side of the skirt 4 by the pair of vertically ex tending slots 14 and the adjoining transverse slot l5.

The peculiar slotting of the skirt on the pin boss sides 1 by'the L-shaped slots l0 and the slots l4 and '15 on the compression thrust side 6 of the skirt, obviously provides a piston skirt which is resiliently flexible on the pin boss sides beneath the pin bosses and on the compression thrust side of the skirt, whereas, and by reason of there being no slotting on the power thrust side of the skirt and the parts of the skirt which support the pin bosses, the power thrust side 5 of the piston is therefore capable of presenting a solid thrust side to the cylinder wall, as distinguished from the compression thrust side 6 presenting a resiliently flexible thrust side to the cylinder wall.

Formed in the power thrust side of the skirt 4 is a threaded transverse opening l9 and formed in the compression thrust side 6 of the skirt, is an opening 20 in alinement with the threaded opening l9, said openings being formed in the skirt adjacent the lower piston ring recess 2, and mounted in said openings is a steel tie bolt 2|. The steel tie bolt 2| has a threaded end 22 which is engaged in the threaded opening I9,-

the other end of said bolt having a grooved head 23, which is nested in a recess 24 and mounted on said bolt is an oil tempered coil spring 25 having one end in abutment with the inner periphery of the compression thrust side 6 of the skirt, and the other end of the spring bearing against a lock nut 26 which is jammed against the inner periphery of the power thrust side 5 of the skirt.

In machining a piston of this improved character, the diameter of the skirt is ground to the diameter of the cylinder in which the piston is to be mounted, minus a relatively small clearance for permitting mounting of the piston in sion. Before mounting the piston in the cylinder,

the tie bolt 2|. is adjusted into limiting position for cooperation with'the thrust sides 5 and 6 of the skirt.

In the operation of this improved piston in a cylinder of an internal combustion motor, the small initial clearance given to the skirt diameter will provide for the piston operating in a cool condition before the motor becomes heated without there being any noticeable piston-slap, and

when the motor becomes heated, the expansion of the piston head I across the thrust side diameter will carry the power thrust side 5 of the skirt outward by reason of the power thrust side depending from the side wall 3 of the head.

This action exerts a pulling movement on the threaded end 22 of the tie bolt 2| and the head 23 thereof will draw in the tongue portion i8 on account of the tongue portion being disconnected from the side wall 3 of the head by the transverse slot I5.

The inward pulling movement of the tie bolt 2! along with the expanding travel of the power .thrust side 5 of the skirt, will prevent the tongue portion IS on the compression side from seizing or too tightly engaging the cylinder wall, and simultaneously therewith, the slot 21 will accommodate the circumferential expansion of the lower disposed cylinder bearing portions l1 beneath the pin boss sides and the lower portion of the compression thrust side of the skirt.

Expansion of the piston head I across the pin bossdiameter thereof, will cause outward expanding movement of the pin bosses 8, but as the compression thrust side 6 of the skirt 4 is freed from the pin bosses by the L-shaped slots Hi, this outward expanding movement is prevented from becoming active on the compression thrust side, and the cylinder bearing portions I! on the pin boss sides. The pin bosses 8 are reinforced by a centrally disposed web 28 which is formed integral therewith and extends upwardly on the inner periphery of the pin boss sides I and across the under side of the head, said pin bosses or pin boss sides, when expanded or moved outward, being prevented from engaging the cylinder wall by the relief or formed inset 9.

As it is the purpose of the invention to provide a piston having a skirt which is capable of automatically adjusting itself to full cylinder bearing contact during changing thermal working conditions, the arrangement of the parts shown and described, obviously provide a piston which is in a sense self-accommodating, so as to simultaneously prevent piston-slap and seizing and at the same time provide a piston which is capable of proper operation in an internal combustion motor without excess clearance.

The provision of the resiliently yieldable tongue shaped portion I8 obviously permits yieldability in the event there is an attempted seizing of the piston due to a dry cylinder, the yielding of the tongue shaped portion to cylinder wall pressure therefore preventing seizing of the piston in the cylinder, and under this condition the coil spring 25 will be caused to yield under cylinder wall pressure, but as soon as this dry condition of the cylinder is overcome, the spring 25 will immediatelybecome active on the tongue shaped portion l8, thereby forcing said portion into limiting engagement with the head 23 of the tie bolt 2|.

As the thrust sides of a piston acquire the most wear, in due time adjustment can be made for expanding the skirt across the thrust sides by releasing the lock nut 26 and withdrawing the tie bolt 2| a desired amount until the proper diameter across the thrust sides has been attained, the lock nut then being secured in position and the spring 25 yieldingly pressing the tongue portion l8 against the head 23 of the tie bolt and holding the skirt to the adjusted size.

Obviously constructional modifications of the device are possible without departing from the spirit of the present invention and therefore it is to be understood that it is not necessary to limit the invention by the terms used in the foregoing description, excepting such as the state of the art may require.

What I claim is:-

1. A piston for an internal combustion moto comprising a head having a side wall, pin bosses, and a pair of thrust sides, one of said thrust sides being formed continuous with the side wall of the head and the other thrust side being separated from the side wall of the head by a transverse slot, a leg depending from the side wall of the head between each pin boss and the separated thrust side, said legs being free from engagement with the pin bosses, a tie member connecting said thrust sides and having a head at one end which is slidably secured in said separated thrust side, and resilient expanding means cooperable at its ends with said thrust sides.

2. A piston for an internal combustion motor comprising a head having a side wall, a skirt continuous with the side wall of the head on one side and having a resiliently flexible part on its opposite side, pin bosses, a leg depending from the side wall of the head to the lower part of the skirt between each pin boss and the flexible part of the skirt, said legs being free from engagement with the pin bosses and the flexible part of the skirt, a tie member connecting opposite sides of the skirt having a head on one end which is slidably mounted in the flexible part of the skirt, and a resilient expansion member mounted over said tie member having its ends respectively engaged with said flexible part and the opposite side of said skirt.

3. A piston for an internal combustion motor comprising a head having a side wall and pin I bosses, a skirt continuous with the side wall of the head on one side and having a tongue shaped portion on its opposite side, a leg depending from the head side wall to the lower part of the skirt between each pin boss and the tongue shaped portion, said legs being separated from the tongue shaped portion and respective pin bosses, and a transversely disposed tie member having respective ends cooperable with said tongue shaped portion and the opposite side of said skirt.

4. A piston for an internal combustion motor comprising a head having a side wall and pin bosses depended from the side wall, a skirt continuous with the side Wall of the head on one side and having a resiliently flexible part separated from the side wall of the head on its opposite side, a leg on one side of each pin boss depending from the side wall of the head for the support of said separated skirt side, said legs being separated from the flexible part and respective pin bosses, and a transverse slot in the skirt beneath each pin boss.

5. A piston for an internal combustion motor comprising a head having a side wall, a skirtcontinuous with the side wall of the head on one side and having a part separated from the side wall of the head on its opposite side, pin bosses extending from the skirt, a pair of legs forming a part of the skirt depending from the side wall of the head for the support of said separated skirt side, each leg being on one side of a respective pin boss and free from engagement therewith, and a transversely disposed resilient expansion member cooperable at its ends with said separated part and the opposite side of said skirt.

6. A trunk type piston having a full skirt and pin bosses extending from the skirt and a flexible part formed in one of the skirt thrust sides which is separated from the head, a leg formed in the skirt on each side of the flexible part and sepa- -beneath a respective pin boss.

rated therefrom, and an L shaped slot in the skirt on each pin boss side in opposing relation from each other and disposed so that the horizontal bar 01 each slot extends beneath a respective pin boss.

7. A trunk type piston having a full skirt and pin bosses extending from the skirt and a flexible part formed in one of the skirt thrust sides which is separated from the head, a leg formed in the skirt on each side of the flexible part and separated therefrom, and an L shaped slot in the skirt on each pin boss side in opposing relation from each other and disposed so that the horizontal bar of each slot extends beneath a respective pin boss and wherein the vertical bar of each slot separates a respectiveleg from a respective pin boss.

8. A piston comprising a head and a skirt having opposing thrust sides, said skirt having one of its thrust sides longitudinally slotted and separated from the head, pin bosses, legs formed in the skirt and being free from engagement with the pin bosses, said legs depending from the head to lower parts of the skirt for supporting said separated thrust side, and a transverse slot formed in the skirt and extending from each leg 9. A piston comprising a head and a skirt having a pair of opposing thrust sides, one 01 said thrust sides being longitudinally slotted and separated from the head, pin bosses extended from the skirt, said head having a side wall, a leg formed in the skirt depending from the side wall of the head to respective lower parts of the skirt adjacent each pin boss, said legs being free from engagement with respective pin bosses, and a from each leg beneath a respective pin boss.

ELMER C. LONG. 

